Electronic components having a MEMS are generally formed by a hermetically closed case inside which the MEMS is mounted. The MEMS may be, for example, a piezoelectric resonator, such as a quartz resonator intended to be connected to an oscillator circuit. Most quartz resonators of small dimensions, which are used, for example, in electronic or electromechanical watches, are tuning fork resonators.
These quartz resonators are usually in vacuum sealed cases, in the case where low frequency signals are generated, delivered by the oscillator circuit, or in an inert gas atmosphere. Further, one portion of the cover may be transparent to a determined wavelength of a light beam so as to allow optical adjustment of the quartz resonator.
Generally, these resonators are mounted in cases, for example made of ceramic, which are relatively flat. These cases include a main hollow portion of parallelepiped shape inside which the resonator is mounted, and a rectangular cover fixed to the main portion.
In order to ensure the sealing between the cover and main portion, a sealing gasket is currently used, made of a eutectic gold and tin based metal alloy which is assembled between the two portions and the assembly is then heated so as to permanently seal the case in a controlled atmosphere.
These gold-tin based alloys have the drawback of using intrinsically expensive materials and having a relatively low melting point, i.e. of around 278° C. This latter feature limits the possible methods used during or after the connection of the case to its medium of use such as a printed circuit board, for example. Indeed, it is clear that no heat treatment higher than 280° C. can be carried out subsequent to the connection, otherwise the case is liable to become unsealed, which, even partially, would result in a loss of hermeticity of the device and thus a loss of resonator performance.